In April 1993, the World Health Organization (WHO) declared tuberculosis (TB) a global health emergency, a distinction never accorded another disease. Two billion people are infected with Mycobacterium tuberculosis (Mtb), leading to eight million new TB cases each year and nearly three million resultant deaths. Despite the development of effective chemotherapies to treat TB, this public health crisis persists, fueled by the burgeoning HIV co-epidemic. [unreadable] [unreadable] A considerable obstacle to TB control is the emergence of drug-resistant disease. Multidrug-resistant strains of TB (MDRTB) persist in approximately 50 million people worldwide and lead to nearly 500,000 new cases of MDRTB each year. MDRTB is much more difficult and expensive than drug-susceptible TB to treat, and requires up to two years of therapy with a combination of drugs, including second-line drugs that are less potent and more toxic than the first-line therapies. An even more disquieting development in this public health crisis is the global distribution of strains of extensively drug-resistant TB (XDRTB), which may originate from poor management of MDRTB cases. These XDR strains are resistant to isoniazid and rifampin, as well as to key second-line drugs; as a result, they are even more difficult to treat than MDRTB, and are often a death sentence for those infected. [unreadable] [unreadable] We propose to develop a novel rapid diagnostic for antibiotic susceptibility testing for TB that combines the best characteristics of two proven technologies. The first is the ability of mycobacteriophage to specifically infect only viable and translationally competent Mycobacteria following drug treatment; detection of a translated product from the phage can then serve as a marker for antibiotic resistance. The second is the exquisite sensitivity of various nucleic acid amplification and detection technologies, which have the capability to sense only a few copies of a particular sequence. Our hope is that the marriage of these two technologies will allow for the very sensitive and specific determination of the antibiotic susceptibility profile of TB. Further, we believe that it shows great promise for being able to be performed directly on sputum specimens. [unreadable] [unreadable] There are eight million new cases of tuberculosis (TB) each year and nearly three million resultant deaths. A considerable obstacle to TB control is the emergence of drug-resistant disease. In this grant application, we propose to develop a novel method for the detection of drug-resistant TB that would be significantly faster and less expensive than existing methods, allowing patients with drug-resistant disease to be immediately treated with appropriate drugs to prevent its further transmission. [unreadable] [unreadable] [unreadable]